const fp = require('lodash/fp');

const cars = [
  { name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true },
  { name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: true },
  { name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false },
  { name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false },
  { name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true },
  { name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: true },
]

// 练习1
let isLastInStock = fp.flowRight(fp.prop('in_stock'), fp.last);
console.log(isLastInStock(cars));

// 练习2
let getFirstName = fp.flowRight(fp.prop('name'), fp.first);
console.log(getFirstName(cars));

// 练习3
let _average = xs => fp.reduce(fp.add, 0, xs) / xs.length;
let averageDollarValue = function(cars) {
  let dollar_values = fp.map(function(car) {
    return car.dollar_value;
  }, cars);
  return _average(dollar_values);
};
console.log(averageDollarValue(cars));
// 组合的方式实现averageDollarValue
averageDollarValue = fp.flowRight(_average, fp.map(({ dollar_value }) => dollar_value));
console.log(averageDollarValue(cars));

// 练习4
// 再map方法中将字符串操作进行转小写和替换字符串的组合
let _underscore = fp.replace(/\W+/g, '_');
const sanitizeNames =
  fp.map(name => fp.flowRight(_underscore, fp.toLower)(name));
console.log(fp.split(',', 'a,b,c,d'));
console.log(sanitizeNames(['Hello World', 'Hello Js']));
